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TOPIC: Ancient Impact
Blobrana


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Murray Springs micro-tektites
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Fragments of tektites, natural glass objects, discovered by a team of geologists and geochemists help support a theory that a meteorite may be responsible for the sudden climate change that devastated large mammals in North America 11,000 years ago. While critics of such an extraterrestrial event have in the past noted the lack of evidence, the micro-tektites from the Clovis-age Murray Springs in Arizona could cause them to rethink their position.

These micro-tektites contain iron oxide spherules in a glassy iron-silica or silica matrix, which is one indicator of a possible meteorite impact. The spherules also contain elevated concentrations of vanadium and sulphur, and small amounts of titanium - lead author Mostafa Fayek of the University of Manitoba in Winnipeg.

The University of Tennessees Larry Anovitz, who works in ORNLs Measurement Science and Systems Engineering Division, noted that the chemistry of the spherules and matrix is consistent with that of tektites associated with other meteorite impact sites such as those found in Romania. Funding was provided in part by the Natural Science and Engineering Council of Canada.  

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Blobrana


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RE: Ancient Impact
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Drifting memories of the ruined Poompugar came back to me while I was moving around the altered coastal line of Mullaitivu, and the prehistoric asteroid, which struck the Planet.
Geologists Gary Byerly, Xiaogang Xie, Donald Lowe and Joseph Wooden of Louisiana State and Stanford universities published in the journal SCIENCE about the strike.
The scientists said, "There was almost certainly life at that time. Primitive, bacterial life, and if the impacts were made by a meteor 20 miles in diameter, they would have killed everything on the surface of the Earth.
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Blobrana


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The moon's pockmarked face stands as mute witness to the chaos that reigned in the solar system in the eons following the Big Bang, when objects flying at unimaginable speeds slammed repeatedly into the lunar surface.
Such impacts surely occurred at least as frequently on Earth early in its history, when the impact rate was 1,000 times higher than it is now. But the results of those ancient events aren't nearly as obvious as they are on the moon.

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Blobrana


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Title: Paleoindian demography and the extraterrestrial impact hypothesis
Authors:  Briggs Buchanan, Mark Collard,  Kevan Edinborough

Recently it has been suggested that one or more large extraterrestrial (ET) objects struck northern North America 12,900 ± 100 calendar years before present (calBP) [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 104: 1601616021]. This impact is claimed to have triggered the Younger Dryas major cooling event and resulted in the extinction of the North American megafauna. The impact is also claimed to have caused major cultural changes and population decline among the Paleoindians. Here, we report a study in which 1,500 radiocarbon dates from archaeological sites in Canada and the United States were used to test the hypothesis that the ET resulted in population decline among the Paleoindians. Following recent studies [e.g., Gamble C, Davies W, Pettitt P, Hazelwood L, Richards M (2005) Camb Archaeol J 15:193223), the summed probability distribution of the calibrated dates was used to identify probable changes in human population size between 15,000 and 9,000 calBP. Subsequently, potential biases were evaluated by modeling and spatial analysis of the dated occupations. The results of the analyses were not consistent with the predictions of extraterrestrial impact hypothesis. No evidence of a population decline among the Paleoindians at 12,900 ± 100 calBP was found. Thus, minimally, the study suggests the extraterrestrial impact hypothesis should be amended.

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Blobrana


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Meteorite impacts not only alter life on Earth, they alter the rocks in ways that can create valuable mining resources. Finding them could speed up the process of locating mineral wealth, says an Australian expert.

"It is not widely appreciated that an estimated 25 per cent of the world's impact structures are associated in some way with economic or sub-economic mineral and petroleum resources" - Peter Haines a sedimentologist with the Geological Survey of Western Australia.

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Blobrana


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10 Greatest Major-Impact Craters on Earth

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Blobrana


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or several months following the comet strike, the skies rained precious stone and metals, the researchers speculate. Diamonds drizzled down by the tons.
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Blobrana


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Exploding Asteroid Theory Strengthened by New Evidence Located in Ohio, Indiana
Was the course of life on the planet altered 12,900 years ago by a giant comet exploding over Canada? New evidence found by UC Assistant Professor of Anthropology Ken Tankersley and colleagues suggests the answer is affirmative.

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Blobrana


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Title: Early Archean spherule beds: Chromium isotopes confirm origin through multiple impacts of projectiles of carbonaceous chondrite type
Authors: Frank T. Kyte, Alex Shukolyukov, Günter W. Lugmair, Donald R. Lowe, and Gary R. Byerly

Three Early Archean spherule beds from Barberton, South Africa, have anomalous Cr isotope compositions in addition to large Ir anomalies, confirming the presence of meteoritic material with a composition similar to that in carbonaceous chondrites. The extraterrestrial components in beds S2, S3, and S4 are estimated to be ~1%, 50%60%, and 15%30%, respectively. These beds are probably the distal, and possibly global, ejecta from major large-body impacts. These impacts were probably much larger than the Cretaceous-Tertiary event, and all occurred over an interval of ~20 m.y., implying an impactor flux at 3.2 Ga that was more than an order of magnitude greater than the present flux.

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Blobrana


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It must have seemed like the end of the world to those who witnessed it.
A huge, fiery ball hurtled to Earth, followed by an enormous explosion and a hailstorm of speeding debris like shrapnel.
Many of the woolly mammoths, horses, bears and bison in the region may have died. But evidence of the apocalyptic event survived, preserved in their remains for more than 30,000 years until they resurfaced at a motel in Arizona.
This evidence has some scientists shifting their thinking about extinctions and looking to space for answers.

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